German Patent No. 196 23 989 describes a spark plug having a tubular metallic housing in which an insulator is embedded, a rod-shaped internal conductor configuration being arranged in the insulator, the internal conductor configuration including a terminal stud, a current-limiting resistor, a coated contact pin and a nail-shaped platinum center electrode. Also attached to the housing are at least two, preferably four, ground electrodes, bent in toward the center electrode.
In comparison to known spark plugs, the advantage of the spark plug according to the present invention is that by sealing in the resistor in advance, spark pits in the ceramic are reduced and, thus, an adequate long-term stability and service life of the spark plug are given, accompanied by high spark energies and positive polarity of the ignition voltage. Important to the present invention in this case is that the resistor pack in the resistor seal has a larger cross-section on the terminal side facing away (farther away) from the combustion chamber than the resistor pack on the side facing (nearer) the combustion chamber. This has the advantage of providing a high stability with respect to capacitive stresses in the region of the electrodes, despite the spatial restriction and the use of a relatively small resistor pack.